The present invention relates generally to devices controlling or conditioning the temperature of electronic components which are being stress tested in "burn-in" ovens, or the like, to determine characteristics of the electronic components. Specifically, the present invention relates to an apparatus that impinges a flow of gas on each electronic component to regulate the temperature of the electronic components in the burn-in oven.
Electronic components, such as silicon chip integrated circuits (ICs) or other semiconductor devices, are subject to early failure during their life cycle. Thus, producers of these electronic components have found it cost-effective to rigorously stress test electronic components prior to their inclusion in electronic products. By conducting such stress testing, and by the elimination of failed, under-performing electronic components in final test, the reliability of the electronic components that pass the stress test is greatly enhanced.
During such tests, or "burn-in", burn-in boards are used to support a number of electronic components inside an oven. Burn-in ovens are typically large enough to hold several racks of burn-in boards with each burn-in board holding several electronic components.
Within the oven, temperature gradients typically cause a variation in temperature across a burn-in board of approximately 20%. Also, there is hysteresis as the oven heating elements cycle on and off in order to maintain a selected temperature. While burn-in procedures have been generally acceptable to date, variations in temperature experienced by the electronic components have slowed testing and created inefficiencies. It is desirable to overcome temperature gradients within the oven so as to subject all of the electronic components to the selected temperature. Ideally, electronic components tested in burn-in ovens should be kept within a band of 2.degree. C. at 150.degree. C. for testing and stressing.
Current burn-in procedures for higher power devices include several problems. For example, the power of each component may vary by 30 percent. Also, thermal impedance may vary from one component to another by a second order effect. Present burn-in procedures often destroy higher power electronic components. Electronic component temperatures continue to vary even if the electronic components are bathed in a single stream of air.
For the foregoing reasons, there exists a need for a burn-in oven that provides electronic components inside the burn-in oven with a uniform, or individual, temperature that is cost-effective and subject to real-time adjustments during burn-in so as to efficiently test electronic components.